It is often necessary to inspect passages such as water wells, bore holes, pipes, pipelines, tanks or underground cavities. This might be done in order to pinpoint damaged casings, obstruction, or other conditions that can be repaired. A down hole inspection might also be used to located lost or damaged pumps or tools. By capturing the inspection of a borehole or water well on a video tape, a record of the well's condition can be captured and saved.
In a typical down hole surveying system, the down hole tool has a single camera which allows for downward viewing only. This eliminates the possibility of examining the sides of a wall or a bore hole.
One solution to this problem has been to use mirrors in conjunction with a downward camera to capture images of the side of the bore hole. This solution is inadequate because it produces poor image quality, produces an image of reduced size and provides a reversed image.
Another solution proposed to address this problem is a two camera system. One such system is disclosed in U.S. Pat. No. 5,652,617, entitled “Side Scan Down Hole Tool Having Two Cameras” and issued to Barbour on May 31, 1996.
This system includes one camera pointed straight down the bore hole and operable to view down the hole and a second camera mounted to provide a close up of the side of the borehole. One drawback of this system is that an added camera involves added expense, additional complexity and takes-up additional space.